1. Field of the Invention
The instant invention relates to a wear compensating pin assembly to be utilized with chain linkage of the type used in overhead conveyors employed in environments such as industrial plants for conveying parts from one station to another.
2. Background Art
A conventional chain assembly comprises a pair of side links connected by a pin to a center link. Each pair of side links is pinned to a corresponding center link which, in turn, is pinned to the next adjacent pair of side links. Conveyor chains of this type are normally driven by gears which engage an end of the center link between the side links. Accordingly, it is important to maintain the pitch of the chain assembly as uniform as possible, the pitch being the distance between the location of a pin seated in one center link and the same seat in the next adjacent center link. Furthermore, it is important to maintain the overall length of the chain uniform in use. However, as the chain assembly is used, wear occurs on each pin as well as on the respective seats in the center link and side links which coact with the pin, resulting in a change in the pitch and elongation of the entire chain assembly.
Examples of chain assemblies are disclosed in the U.S. Pat. Nos. 1,109,808 to Wilmot, 1,557,172 to Klein et al, and 2,507,458 to Rose. The Klein patent discloses a worn pin having a worn central portion and worn side portions. The Klein patent does not disclose or imply a pin construction having a central protrusion on one side and a lateral protrusion on both opposite sides of the central protrusion to take up the slack of a worn chain and link to restore the chain to the original length and pitch. On the contrary, the pin taught by the Klein et al patent discloses the method of rotating the pin at 180.degree., this method not taking up for the worn areas of the chain links. The Wilmot patent discloses a pin for a chain link assembly wherein the pin includes a central cylindrical portion and elliptical side portions. The Rose patent discloses a pin for a chain link assembly including an elliptical shank. In other words, the constructions taught by the Wilmot and Rose patents include pins having elliptical portions for taking up slack between worn links or between new links of a chain. However, these constructions are limited in that the elliptical diameter of those pins cannot be greater than the opening of the chain link so as to allow the pins to be disposed within the links. The instant invention provides a link pin for returning a worn chain to its original pitch and length wherein all the cross sections through the subject link pin are substantially cylindrical, and no one cross section of the subject link pin is greater than the cross section of the original cylindrical pins which could be inserted through the chain link. Accordingly, a single link pin constructed in accordance with the instant invention may be used to shorten the length of the unworn chain a predetermined amount taking the place of up to four elliptical pins to shorten the chain the same amount because a single elliptical pin may have an elliptical diameter of sufficient size but could not be inserted through the link opening, whereas, a single pin constructed in accordance with the subject invention would have no diameter greater than the diameter of the opening through the chain link.